Earlier this summer scientists from New England Biolabs in Beverly, Mass., announced they had discovered a new way to copy DNA. Their method, called helicase-dependent amplification (HDA), reportedly mimics in vivo DNA replication better than PCR does.1 Moreover, HDA can be conducted at a single temperature, thus obviating the need for thermocycling. In the future, perhaps the limitations of PCR – that it is reagent intensive, requires expensive equipment, is difficult to reproduce, and generally is not linear – will be surmounted by new technologies, HDA or otherwise.
In the beginning, there was Taq. Now there are thermostable enzymes, and lots of them. First isolated from the heatloving Thermus aquaticus, Taq DNA polymerase was, for many years, the enzyme for PCR. Taq may still be the industry standard, but its error rate – nearly 1 × 10-4 to 2 × 10-5 mistakes per base pair – is high compared to ...
